Various means are known to sequentially fire a photoflash lamp array utilizing a circuit board having the firing circuitry deposited directly thereon. The use of radiation-sensitive switches and fuses connected in said circuitry is also known. A photoflash unit of this general type is described in U.S. Pat. No. 3,894,226, issued July 8, 1975, to James M. Hanson, wherein the particular flash lamps employed provide an open circuit condition between the lead-in wires upon flashing and radiation-sensitive switches permit the next lamp to be flashed. It is also recognized in U.S. Pat. No. 3,532,931, issued Oct. 6, 1970, to P. T. Cote et al, that fuse means are useful when the flash lamps are not reliably non-shorting upon flashing to assure that an open circuit condition will result. By such means, an already fired flash lamp exhibiting relatively low resistance between the current conductors by reason of a shorted condition cannot thereafter absorb part of the electrical energy when the next firing pulse is applied to the next flash lamp and thereby possibly preclude the desired firing sequence from taking place.